High voltage battery systems are composed of battery cells and a multiplicity of components. A battery system with Li-ion cells usually requires an electronic controller which monitors the cell voltage and the temperature, determines the operating voltage, the insulation resistance and the state of charge of the system and, if appropriate, controls disconnection devices. In the case of use in electrical or hybrid motor vehicles, the energy of the battery is transferred by a power converter to one or more electric machines, or vice versa (fed back). The power converter generates in this context a PWM alternating current (AC) from the direct current (DC) of the battery by way of power transistors.
As a result of the high-frequency control of the power transistors in the power converter, interference signals occur on the DC lines between the battery and the power converter. Such interference signals can also be generated by a charging device or a DC/DC converter which is connected to the high voltage bus. It is known to arrange such battery systems in a closed housing. This serves, on the one hand, to protect the battery components against external influences, and on the other hand to protect the surroundings from the voltage which is present inside the battery. The electronic control units are usually arranged inside the battery housing. Interference signals are also generated by the switching processes of these control units.
As described, the components of a battery are subjected to interference signals which are external to the battery as well as to interference signals which are internal to the battery. These interference signals can have a considerably adverse effect on the functional capability of the battery system. The high-frequency interference signal, which starts, for example, from a power converter, has a considerable adverse effect on, in particular, the sensing of the system voltage. Electronic units can also be damaged by particularly high voltage peaks.
DE 10 2008 041 518 A1 describes an accumulator monitoring system with a potential isolating circuit for connecting a data processing circuit and a sensing circuit.
DE 10 2010 029 461 A1 presents direct current source arrangements with coupling to a housing and using capacitors and EMI filters.
A device for controlling and monitoring direct voltage sources connected in series is presented in DE 10 2010 030 353 A1. Each direct voltage source is assigned a cell monitor. Galvanic decoupling of the cell monitor and central control unit is carried out by way of an isolation module.
DE 36 26 593 A1 discloses a device for accommodating a battery and electronics in a screening fashion. The electronics are accommodated in the battery housing.
DE 601 33 613 T2 describes the screening of a high voltage part, and DE 11 2008 003 519 T5 discloses the use of drilled cables in a bidirectional energy management system.